WASHINGTON — U.S. Attorney General Eric Holder on Monday called the shooting death of unarmed black teenager Trayvon Martin “unnecessary,” raising questions about whether he believed the shooter, George Zimmerman, acted in self-defense.

A jury in Sanford, Florida, found Zimmerman not guilty of second-degree murder and manslaughter after a three-week trial in which defense lawyers argued that Zimmerman, a neighborhood watch volunteer, shot Martin in self-defense.

Zimmerman, 29, has gone into hiding since the verdict. Friends, family and defense lawyers have said he will need time to put his life back together and was considering entering law school to help people wrongly accused of crimes.

The attorney general did not indicate whether he intended to bring a federal case, but by referring to the “tragic, unnecessary shooting death of Trayvon Martin,” Holder raised the question of whether he believed Zimmerman acted in self-defense.

Ben Crump, a lawyer for Martin’s divorced parents, Tracy Martin and Sybrina Fulton, said the family would weigh its options regarding a wrongful death civil lawsuit against Zimmerman but for now was still “devastated” by the verdict.

“She cried, she prayed to God, and then she cried some more,” Crump said of Fulton. “She said, ‘I will not let this verdict define Trayvon. We will define our son Trayvon’s legacy.’ It was real inspiring.”

The verdict triggered protests across the United States from disappointed and angry people who said Zimmerman racially profiled Martin, 17, as a possible criminal and pursued him while armed with a fully loaded 9mm pistol.

Immediately following the verdict, civil rights leaders began calling for federal charges, saying the trial in Florida failed to serve justice.

Then on Sunday the Justice Department said it would reopen its investigation into the case, saying experienced prosecutors would determine whether any of the “limited” applicable civil rights laws had been violated, and whether the case met guidelines for bringing a federal case after a matter has already been decided in state court.

By finding Zimmerman not guilty of second-degree murder, the Seminole County jury rejected the charge that Zimmerman acted with ill will, spite or hatred.

The remarks by Holder, the chief U.S. prosecutor and an appointee of President Barack Obama, came on Monday as he addressed a convention of Delta Sigma Theta, a black sorority.

The U.S. Matthew Shepard and James Byrd Jr. Hate Crimes Prevention Act of 2009 would require the government to prove beyond a reasonable doubt that Zimmerman, who is white and Hispanic, shot Martin because of race.

More than 800,000 people signed an online petition of the National Association for the Advancement of Colored People asking Holder to file civil rights charges against Zimmerman, the association said on Monday.

Martin’s family, which has already received a confidential settlement from the homeowners’ association in the gated community where the shooting took place, was also considering a civil suit against Zimmerman.

For now Crump was turning his attention to the federal government, contending it was a civil rights violation for Zimmerman to profile Martin as criminal based on race.

“Does this [verdict] mean anybody packing a gun can come up and chase our children? And then when our children defend themselves, they can be killed and this is allowed?” Crump said.

The verdict weighed heavily on the NAACP, which was holding it annual convention in Orlando, a few miles from Sanford.

The NAACP would work to help overturn self-defense laws like those in Florida that helped Zimmerman’s defense, and to promote anti-profiling laws, the group’s president, Benjamin Jealous, said.

“Just like the battle against lynching, the battle against urban street violence, the battle against the bad guys killing our kids and the good guys killing our kids is one that we have to prepare to be a generational battle,” Jealous said.

“The reality is in this country, the world’s greatest democracy, it should not be the case that any child has to fear both the robbers and the cops. Both the bad guys and the good guys,” Jealous said.

Additional reporting by Daniel Trotta in New York and Barbara Liston in Orlando; Writing by Daniel Trotta; Editing by Steve Orlofsky.